pom.xml

<plugin>
  <artifactId>kotlin-maven-plugin</artifactId>
  <groupId>org.jetbrains.kotlin</groupId>
  <version>${kotlin.version}</version>

  <configuration>
      <compilerPlugins>
          <plugin>all-open</plugin>
          <plugin>jpa</plugin>
      </compilerPlugins>

      <pluginOptions>
          <option>all-open:annotation=javax.persistence.Entity</option>
      </pluginOptions>
  </configuration>

  <dependencies>
      <dependency>
          <groupId>org.jetbrains.kotlin</groupId>
          <artifactId>kotlin-maven-allopen</artifactId>
          <version>${kotlin.version}</version>
      </dependency>
      <dependency>
          <groupId>org.jetbrains.kotlin</groupId>
          <artifactId>kotlin-maven-noarg</artifactId>
          <version>${kotlin.version}</version>
      </dependency>
  </dependencies>
</plugin>